Protect voltage regulator

[Derekk02]

Hi all,

I want to make 5V. I'm using a voltage regulator with a Vin-max = 6V and Vdropout = 0,4V.
How can I protect the regulator for higher voltages than 6V?

For example, can I use a 5V6 zener diode to protect the vreg?

 

[Tahmid]

Which regulator are you using? What is the current you're drawing? What is the typical input voltage? Why not just use 7805?

 

[goldsmith]

Dear Derekk
Hi
At first , as Tahmid told , which regulator you're referring to ? though , there are many ways available , such as an op amp and two voltage divider resistor to measure input voltage and affect a dominant feed back loop . BTW , why protection ? is that harmful for your regulator ? ( some volts , higher ? )
Best Wishes
Goldsmith

 

[Derekk02]

I use the MCP1700T-5002. It can deliver 250mA at 5V. I need about 150mA.
datasheet: **broken link removed**

Inputrange: 6V (max. 6.5V)
Output: 5V

I'm using this voltage regulator because this one has a very low drop-out voltage.

How can I protect it for higher voltages at the input? For example 10V?

 

[Tahmid]

Do you need the low drop-out voltage? What is your standard input voltage - the regular expected input voltage? Where is it coming from? Is there an actual risk of high voltage at the input?

As for the protection, you can use a zener clamp. Or you can have an overvoltage protection circuit using a comparator, where the comparator first decides if the input voltage is within the allowable range and if it is, then turns on a switch (transistor or MOSFET) which lets current flow to the regulator. If the input voltage (detected by the comparator) is greater than 6V, then the switch is off so that no current flows to the regulator.

Hope this helps.
Tahmid.